Kinetics and mechanism of the oxidation of chromium (III) complex involving the antifibrinolytic drug Tranexamic acid by periodate

Tranexamic acid (TXA) have antifibrinolytic properties and finds wide applications in pharmaceuticals, most used in cardiac, orthopaedic, urological, gynaecological, and obstetric surgery. Complexes of tranexamic acid with some metal ions show antimicrobial and anti-tumor activity. Oxidation-kinetic study is of much importance in understanding the mechanistic profile of Cr-TXA complex in biological systems. Kinetics of oxidation of [CrIII(TXA)(H2O)5]2+ by periodate has been spectrophotometrically studied under pseudo order conditions over 293-313 K, pH (3.20-4.20) range, and ionic strength of 0.30 M for a set of periodate concentrations. The initial oxidation product is the unstable Cr(V) which is then oxidized to the final product of Cr(VI). The reaction is first order dependent on complex concentration. The pseudo-first order rate constant, kobs increased with decreasing proton concentration, indicating that the deprotonated form of the chromium (III) complex is the reactive species. An inner sphere mechanism has been proposed for the oxidation process. The thermodynamic activation parameters are also reported.